Jessica Simpson has slammed Carrie Underwood and her claims that Tony Romo "still" calls her - saying she laughed when she heard about it.

Jessica Simpson was on the 'Woody and Jim' radio show this morning when they asked her about Carrie's claims.

"Tony and I both laughed at that. We got a chuckle out of it," Jess said. "I know it's not true -- I looked at his call log. I'm kidding!"

"If Tony wanted to call her...or wanted to be with her, he would."

Ouch... Video of Jess on the radio show is here! O.K., so maybe catfight was a stretch but... meowwww...